Need help with post crash analysis of Pixhawk! pls

I am sad to report that one of my pixhawk drones had a serious issue in flight during an auto mission. The craft took off in loiter mode and flew stable. Auto mode was activated and it started to fly the mission. It was programmed to fly at 8.5 m/s. It flew along the correct heading but then started to accelerate, and reverse in a toilet bowl formation crashing sideways into the ground. I have looked at the log file, but have limited experience in this.

Log File C:/Users/Jasper/AppData/Local/Temp/tmp521B.tmp.log
Size (kb) 3198.0126953125
No of lines 42688
Duration 0:03:02
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = FAIL - Truncated Log? Ends while armed at altitude 5.12m
Test: Compass = FAIL - Large change in mag_field (101.98%)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.34, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = FAIL - 17 slow loop lines found, max 11.58% on line 40942
Test: Pitch/Roll = FAIL - Roll (-118.28, line 42666) > maximum lean angle (45.00)
Test: Thrust = GOOD -
Test: VCC = GOOD -

A low res video of in flight footage can be seen at this link:

It seems that nobody can shed any light on what they think went wrong in this flight. I must say I have seen some contributors to this forum give excellent analysis and interpretation of the probable causes of incidents or problems. Still I would appreciate if somebody could have a look.

Some of your vibrations look a little high too and get progressively worse through the flight.
Possibly caused the external compass to come loose causing the toilet bowling.

Thanks for your input MarkM,
I just received the quad from my friend, in may pieces though!. The external gps compass module is indeed loose inside the casing. The orientation however was not disturbed due to the cable configuration holding it in place. Do you think the additional vibrations experienced by the “loose” gps module could have caused the compass malfunction? Bench testing now reveals a perfectly functioning gps and compass…